Disposal of waste material, which can be hazardous and toxic, in landfills and by incineration has become an increasingly difficult problem because of diminishing availability of disposal space, strengthened governmental regulations and the growing public awareness of the impact of hazardous substance contamination upon the environment. Release of hazardous wastes to the environment can contaminate air and water supplies thereby diminishing the quality of life in the affected populations.
To minimize harmful environmental effects of hazardous waste disposal, methods must be developed to convert these wastes into benign, and preferably, useful substances. In response to this need, there has been a substantial investment in the development of alternate methods for suitably treating such wastes. One of the most promising new methods is described in U.S. Pat. Nos. 4,574,714 and 4,602,574, issued to Bach et al., and includes destroying organic hazardous wastes by dissociating the waste in molten metal. Atomic components of the wastes are reformed in the molten metal to generate environmentally acceptable products, such as hydrogen and carbon oxide gases.
A common method of injecting wastes into molten metal baths is through submerged lances. However, most lances are readily consumed by heat released during exothermic reaction of the waste with oxygen, particularly in the presence of ferro alloys in the molten metal bath. Similarly, lances commonly dissolve during exposure to the high temperature of the metal or metal oxide phase that typically exists in molten baths.
As a consequence, lances are often positioned in the slag phase and above the molten metal, or at a metal/slag interface. Another attempt to improve the durability of submerged lances is to insulate them with refractory outer layers. However, in order to provide sufficient insulation and chemical protection of the refractory material from attack by molten metal or slag, a coolant must generally also be injected to prevent rapid destruction of the lances. One method of injecting the coolant is through an annular conduit between a central waste composition injection tube and a refractory insulating tube. The coolant is conducted through the annular conduit and is discharged into the molten metal bath through perforations in the refractory tube to thereby cool the lance. However, refractory tubes typically are very brittle and are susceptible to failure in the molten metal bath. Moreover, submersion of the lance deep into the molten metal is important for achieving essentially complete dissolution and consequent enhanced processing of toxic or hazardous waste.
Therefore, a need exists for an apparatus and a method which overcome or minimize the above-mentioned problems.